Deconstructing the crustacean squat lobster genus

Unravelling the evolutionary history of taxa requires solid delimitation of the traits characterising these. This can be challenging especially in groups with a highly complex taxonomy. The squat lobster family Munididae contains more than 450 species distributed among 21 genera, Munida being the most speciose (~300 species). Previous phylogenetic studies, based on a small part of the diversity of the group, have suggested polyphyletic origins for Munida and the paraphyly of Munididae. Here, we use an integrative approach based on multi-locus phylogenies (two mitochondrial and three nuclear markers) paired with 120 morphological characters, to resolve taxonomic and evolutionary relationships within Munididae. Our study covers ~60% of the family’s known diversity (over 800 specimens of 291 species belonging to 19 of the 21 genera collected from the Atlantic, Indian and Pacific oceans). Using this information, we confirm the validity of most genera, proposing new ones in cases where the genetic analyses are compatible with morphological characters. Four well-defined munidid clades were recovered, suggesting that new genera should be erected in the currently recognised Munididae (three for the genus Agononida and eleven in Munida), and the genus Grimothea is resurrected. A key to all genera of the family is presented. Molecular clock estimates and ancestral biogeographic area reconstructions complement the taxonomic profiles and suggest some explosive diversification within Munididae during the Cretaceous and the Palaeogene. Further anagenetic events and narrow sympatry accounting for changes in distribution indicate a more limited dispersal capacity than previously considered. Our study unravels how diversification may occur in deep waters and further highlights the importance of the integrative approach in accurately delineating species in understanding the history of a family and the factors driving the evolution. ZooBank LSID: urn:lsid:zoobank.org:pub:16A61C4A-8D96-4372-820F-8EBDF179B43C

Homoplasy and morphological stasis revealed through multilocus phylogeny of new myrmecophilous species in Armadillidiidae (Isopoda: Oniscidea)

The terrestrial isopod family Armadillidiidae presents higher diversity in karstic areas, with fewer species present in areas with reduced suitable subterranean habitats, such as siliceous sandy soils. Myrmecophily, although not widespread in the family Armadillidiidae, can help these animals to colonize sandy substrates, as is observed in several populations of myrmecophilous Armadillidiidae species in central and southern Spain. Morphological examination and multilocus phylogenetic analyses, including mitochondrial DNA (Cox1) and nuclear DNA (18S, 28S and H3) markers, indicate that these myrmecophilous populations represent four new taxa: Iberiarmadillidium pinicola gen. & sp. nov., Iberiarmadillidium psammophilum sp. nov., Iberiarmadillidium sakura sp. nov. and Cristarmadillidium myrmecophilum sp. nov. Some of the main diagnostic characters used in the taxonomy of Armadillidiidae are not clearly apomorphic. Among head morphologies, Eluma type seems to be the ancestral state, being typical of several unrelated lineages; duplocarinate and Armadillidium types are derived states observed in unrelated lineages. The presence of a schisma is a convergent character state, because it has been identified in several taxa nested in unrelated clades. The newly described taxa present patterns of morphological stasis and homoplasy, likely to be associated with their shared myrmecophilous habits. The generic taxonomy of the family needs a deep revision including phylogenetic approaches and thorough taxon sampling.

Revision of the squat lobsters of the genus Phylladiorhynchus Baba, 1969 (Crustacea, Decapoda, Galatheidae) with the description of 41 new species

The genus Phylladiorhynchus Baba, 1969 currently contains 11 species, all occurring in the shallow waters and on the continental shelf of the Indian and Pacific oceans. Recent expeditions in these oceans have resulted in the collection of numerous new specimens in need of analysis. We have studied this material using an integrative approach analysing both morphological and molecular (COI and 16S) characters. We describe 41 new species and resurrect three old names: P. integrus (Benedict, 1902) and P. lenzi (Rathbun, 1907), previously synonymized with P. pusillus (Henderson, 1885), and P. serrirostris (Melin, 1939), previously synonymized with P. integrirostris (Dana, 1852). Most species of the genus are described and illustrated. Some species are barely discernible on the basis of morphological characters but are highly divergent genetically. Species of Phylladiorhynchus are mainly distinguishable by the number of epigastric spines and lateral spines of the carapace, the shape and the armature of the rostrum, the number and pattern of the ridges on the carapace and pleon, the shape of thoracic sternite 3 and the armature of the P24 dactyli. A dichotomous identification key to all species is provided.

Descriptions of eleven new species of squat lobsters (Crustacea: Anomura) from seamounts around the Yap and Mariana Trenches with notes on DNA barcodes and phylogeny

Seamounts are well known for the high biodiversity and endemism of their macrobenthic fauna. Hundreds of squat lobster species from seamount environments have been reported in recent years, but squat lobster fauna on the seamount groups around ocean trenches in the tropical West Pacific are still poorly known. In this paper, we describe 11 new species (two Munida, three Munidopsis, one Sternostylus, one Uroptychodes and four Uroptychus) based on specimens collected during expeditions to seamounts around the Yap Trench and Mariana Trench. Of these species, six belong to the superfamily Chirostyloidea and five belong to Galatheoidea. We also provide DNA barcode data for three genes to support the taxonomic status of these new species. The morphological variations, genetic differentiation and phylogenetic relationships of these species are discussed.

Limited long-distance dispersal success in a Western European fairy shrimp evidenced by nuclear and mitochondrial lineage structuring

Anostraca are known by their ability for long-distance dispersal, but the existence in several species of deep, geographically structured mtDNA lineages suggests their populations are subjected to allopatric differentiation, isolation, and prevalence of local scale dispersion. Tanymastix stagnalis is one of the most widespread species of Anostraca and previous studies revealed an unclear geographical pattern of mtDNA genetic diversity. Here, we analyze populations from the Iberian and Italian Peninsulas, Central Europe, and Scandinavia, with the aim to characterize the patterns of genetic diversity in a spatio-temporal framework using mtDNA and nuclear markers to test gene flow among close populations. For these aims we built a time-calibrated phylogeny and carried out Bayesian phylogeographic analyses using a continuous diffusion model. Our results indicated that T. stagnalis presents a deeply structured genetic diversity, including 7 ancient lineages, some of them even predating the Pleistocene. The Iberian Peninsula harbors high diversity of lineages, with strong isolation and recent absence of gene flow between populations. Dispersal at local scale seems to be the prevailing dispersal mode of T. stagnalis, which exhibits a pattern of isolation-by-distance in the Iberian Peninsula. We remark the vulnerability of most of these lineages, given the limited known geographic distribution of some of them, and the high risk of losing important evolutionary potential for the species.

Patterns of morphological diversification in giant Berberomeloe blister beetles (Coleoptera: Meloidae) reveal an unexpected taxonomic diversity concordant with mtDNA phylogenetic structure

Delimiting species boundaries is a complex challenge usually hindered by overlooked morphological diversification or misinterpretation of geographically structured phenotypic variability. Independent molecular data are extremely useful to characterize and understand such morphological diversity. Morphological and molecular variability of the non-phoretic and apterous, widely distributed, giant blister beetles of the genus Berberomeloe, were investigated within and between lineages across most of the distributional range of the genus. We used two mtDNA gene fragments to characterize genetic variability and to produce a time-calibrated phylogeny of the genus. Our results reveal several mitochondrial lineages, allopatrically, parapatrically and sympatrically distributed. Most clades are not distinguishable between each other based on morphometrics. However, no morphometric overlap is observed between two closely related clades, one of them occurring in sympatry with a distantly congeneric species (B. insignis), suggesting that sympatry could trigger morphological diversification. Although most species share a morphometric space, they can be morphologically identified by a combination of easily observed characteristic qualitative features. Based on the concordance between mtDNA clades and morphological units, we describe six new species of Berberomeloe (B. castuo sp. nov., B. comunero sp. nov., B. indalo sp. nov, B. yebli sp. nov., B. payoyo sp. nov. and B. tenebrosus sp. nov.), revalidate two taxa (B. maculifrons comb. nov. and B. laevigatus comb. nov.) and redefine B. majalis.

A new species of Petrolisthes (Crustacea, Anomura, Porcellanidae) inhabiting vermetid formations (Mollusca, Gastropoda, Vermetidae) in the southern Caribbean Sea

Petrolisthes virgilius sp. nov. from the Caribbean Sea of Colombia is described. The new species resembles P. tonsorius morphologically but differs from it principally by its color and habitat. Petrolisthes tonsorius is brown or blueish brown and occurs under intertidal boulders strongly exposed to water movement. Petrolisthes virgilius sp. nov. is pale brown to beige and lives exclusively in intertidal areas dominated by vermetid snails, exposed to heavy wave action. The entangled tubular shells of vermetids are cemented to each other and to a hard substrate like beach rock, forming a microhabitat for the new crab species and other porcellanids of the genera Neopisosoma and Clastotoechus. Large genetic distances between DNA sequences of the mitochondrial 16S rDNA gene from P. virgilius sp. nov. and P. tonsorius confirmed that they comprise different species. Petrolisthes virgilius sp. nov. is the 53rd member of the West Atlantic porcellanid fauna.

Extreme diversity and parasitism of Late Jurassic squat lobsters (Decapoda: Galatheoidea) and the oldest records of porcellanids and galatheids

Galatheoid decapod crustaceans consist of ~1250 species today, but their evolutionary history and origin are poorly known. We studied the largest known fossil galatheoid assemblage, from the Late Jurassic of Ernstbrunn, Austria. This coral-associated assemblage yielded 2348 specimens, arranged in 53 species, 22 genera and six families. Rarefaction analyses show that nearly all taxa have been collected. In addition to abundant Munidopsidae, this assemblage also contains the oldest members of four of the six galatheoid families, including Galatheidae, Munididae, Paragalatheidae and Porcellanidae. We describe the oldest Porcellanidae and Galatheidae to date, and a catillogalatheid: Vibrissalana jurassica gen. et sp. nov., ?Galathea genesis sp. nov. and Galatheites britmelanarum sp. nov. Our re-examination of the oldest claimed porcellanid, Jurellana tithonia, from Ernstbrunn, indicates that it represents a homolodromioid brachyuran, ascribed to Jurellanidae fam. nov. along with Ovalopus gen. nov. The second-oldest claimed porcellanid, Early Cretaceous Petrolisthes albianicus, is transferred to the catillogalatheid Hispanigalathea. We further document that 10.4% of Ernstbrunn galatheoid specimens were parasitized by epicaridean isopods, as shown by swellings in the gill region. Statistical analyses indicate that infestation is near non-random, varying from 0 to 33% for common species. Thus, Late Jurassic coral-associated habitats were key ecosystems in the evolution of galatheoids and their parasites.